In networks designed to deliver services like voice over IP (Internet Protocol), television and video, the network often includes a way to ensure that the service data can be delivered on time. One option to address this issue is to provision the network with enough capacity such that congestion never (or very seldom) occurs. Another option is to provide an admission control mechanism to reduce the risk of networks getting congested.
Often it is the link closes to the user equipment, between the user equipment and the first network node, commonly denoted the first (or last) mile, which presents the largest bandwidth issues. One way of reducing the bandwidth issues is to use equipment limitation, e.g. limit the number of set top boxes a user may have installed.
Admission control can be implemented with policy servers that know the network topology in terms of congestion points. The policy server checks that the congestion points along the delivery path have free resources. If so the resources of the congestion point are reserved and the admission is granted. Otherwise admission is rejected. When the client does not use the resources any longer it returns the bandwidth resources to the policy server.
Set top boxes (STBs) in many cases include the capability to record broadcast content; this is referred to a personal video recorder (PVR). Such STBs can also be provided with multiple tuners to allow recording of one channel while simultaneously live watching of another channel. Scheduled recordings together with live television watching, for potentially multiple STBs in one home, sharing the same first mile capacity, putting strain on the restricted resource which may cause congestion and even service disruption.
This may lead to end user frustration and complaints, causing IPTV operators to be reluctant to allow deployment of multiple STBs, or even multi-tuner STBs in one home.